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SUMMARY:An unexpected role of the plastidial NAD-dependent malate dehydrog
 enase in chloroplast development - Tina Schreier\, Hibberd group
DTSTART:20200123T130000Z
DTEND:20200123T133000Z
UID:TALK131722@talks.cam.ac.uk
CONTACT:71002
DESCRIPTION:The malate dehydrogenase (MDH) family contains multiple conser
 ved isoforms with different subcellular localisations. MDHs catalyse the r
 eversible interconversion of oxaloacetate (OAA) to malate using NAD(P)H as
  cofactor. pdNAD-MDH is one of the two isoforms located within the chlorop
 last. It was previously assumed to play a role in maintaining redox homeos
 tasis\, particularly in the dark and in non-green plastids\, but its exact
  function was unknown. I will demonstrate in this talk that pdNAD-MDH play
 s an important role in early chloroplast development and is therefore esse
 ntial for proper embryo development. The pdnad-mdh knock-out mutant of Ara
 bidopsis is embryo-lethal - a phenotype that could not be complemented by 
 targeting other isoforms of the NAD-MDH family into the chloroplast. This 
 demonstrated that restoring MDH activity alone was not sufficient to suppo
 rt normal embryo development. However\, expressing mutated versions of pdN
 AD-MDH with no catalytic activity complemented the embryo-lethal phenotype
  of pdnad-mdh\, and the complemented plants grew normally. This suggests t
 hat the pdNAD-MDH protein\, but not its enzymatic activity\, is required f
 or normal embryo and chloroplast development. I propose a vital moonlighti
 ng function for the pdNAD-MDH protein in stabilising a large protein compl
 ex involved in protein import at the chloroplast envelope membrane. \n\n
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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